Reciprocal omni-directional rapid scan antenna system



Jan. 14, 1969 A. E. MARSTON 3,422,437

RECIPROCAL QMNI'DIRECTIONAL RAPID SCAN ANTENNA SYSTEM Filed July '7, 1966 IMPINGING PLANE PHASE FRONT TRANSMITTED PLANE PHASE FRONZ Cl CULATOR *P AND RECEWING 22 SYSTEM INVENTOR ARTHUR E. MARSTON BY MM ATTORNEY United States Patent 3,422,437 RECIPROCAI. ()MNI-DIRECTIONAL RAPID SCAN ANTENNA SYSTEM Arthur E. Mar-stun, Alexandria, Va., assignor to the United States of America as represented by the Secretary of the Navy Continuation-impart of application Ser. No. 521,220, Jan. 17, 1966. This application July 7, 1966, Ser. No. 564,509 US. Cl. 343-754 9 Claims Int. Cl. H0lq 19/06; H011 13/00; 11011 3/26 ABSTRACT OF THE DISCLOSURE A rapid scan antenna system by which signals may be transmitted in any direction and other signals may be simultaneously received from that direction or any other direction. The antenna may include two Luneberg lenses each having the same number of ports as there are wave guide horns. The horns, ports and an antenna feed and receiving system are interconnected by four-port circulators to permit simultaneous transmission and reception.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes Without the payment of any royalties thereon or therefor.

This application is a continuatiomin-part of application Ser. No. 521.220v filed Jan. 17, 1966, for Omni-Directional Retrodirective Antenna.

The present invention relates generally to improvements in reciprocal antenna systems which are capable of simultaneous transmission and reception of electromagnetic energy and more particularly to a new and improved reciprocal, omni-directional, rapid scan antenna system whereby a signal can be transmitted in any direction and a signal can be simultaneously received from that direction or any other direction to the exclusion of all other directions.

In the field of scanning antenna systems it has been the general practice to employ a series of linear antenna arrays to permit reciprocal 360 coverage, and it has also been the general practice to employ mechanically rotating systems to permit the simultaneous transmission and reception of electromagnetic energy over 360 of azimuth. Although such devices have served the purpose, they have not proved entirely satisfactory under all conditions of service for the reasons that a considerable amount of complex equipment is required in the case of the use of a series of linear arrays and that, in the case of mechanical scanning, the scan rate is extremely slow and requires a large time interval for a complete scan of the horizon.

The general purpose of this invention is to provide a rapid scan antenna system which embraces all the advantages of similarly employed scanning antenna systems and possesses none of the aforedescribed disadvantages. To attain this the present invention contemplates a unique arrangement of three port circulators, electromagnetic energy refraction or focusing devices such as Lunebery lenses or R-ZR systems, a circular focusing antenna array, and a high scanning rate feed system, whereby a signal can be rapidly scanned for 360 around the horizon while simultaneously receiving a signal from any point on the horizon. Because the present invention provides for an active antenna as opposed to a passive reflector it is able to impress intelligence on the radiated or reradiated signal.

An object of the present invention is the provision of a rapid scan antenna system.

Patented Jan. 14, 1969 Another object is to provide such a device that will rapidly scan a signal through a total of 360 in azimuth.

A further object of the invention is the provision of a reciprocal, omni-dire-ctional, rapid scan antenna system which will simultaneously transmit a signal to and receive a signal from any direction in azimuth.

Still another object is to provide a reciprocal antenna system which is capable of transmitting signals toward any direction in azimuth and which is capable of simultaneously receiving signals from any direction in azimuth.

Other objects and features of the invention will become apparent to those skilled in the art as the disclosure is made in the following description of a preferred embodiment of the invention as illustrated in the accompanying sheet of drawing in which:

The figure shows a perspective view of one embodiment of the invention with some electrical connections not shown for the purpose of clarity.

Referring now to the drawing there is shown in the figure a complete circular ring 4 of receiving and radiating focusing elements, such as wave guide horns some of which elements are designated as 5-9 and -19. Each of the elements in the ring 4 is electrically connected to one port of a four port circulator formed by the combination of two three-port circulators. The connections are exemplified in the figure by the couplings between elements 6 and 7, and circulators 21 and 22. and between elements 17 and 18 and circulators 24 and 2S, respectively.

Each of the circulators, in turn, is electrically connected by means of one of its remaining ports, to a Luneberg lens 35, which has a diameter equal to the diameter of ring 4.

In addition, the circulators 21, 22. 24 and are connected to a second set of circulators 21', 22. 24' and. 25' respectively, which, in turn are connected to Luneberg lens 36.

As exemplified in the figure, circulators 21, 22, 24 and 25 are electrically connected to Luneberg lens by means of ports 6' and 7' and by means of ports 17 and 18', respectively, and circulators 21', 22, 24' and 25' are electrically connected to Luneberg lens 36 by means of ports 6", 7", 17" and 18', respectively. The electrical lengths of the connections between each of the receiving and radiating focusing elements and their respective circulators must be uniform with respect to each other, as must be the electrical lengths between each circulator and its respective Luneberg lens, and between each of the circulators themselves.

In addition, each of the circulators 21', 22' 24' and 25' is electrically connected by means of its remaining port to an element of the high scanning rate feed system 37. As exemplified in the figure, circulators 21, 22, 24' and 25' are electrically connected to the high scanning rate feed system 37 by means of ports 21", 22" 24 and 25", respectively. Here again, the electrical lengths of the connections between each of the circulators and their respective feed system ports must be uniform with respect to each other in order to maintain the necessary phase relationships of energy.

In the operation of the reciprocal, omnidirectional, rapid scan antenna system an electromagnetic signal may be transmitted, for example, from the high scanning rate feed system 37 through one of its ports 22" to circulator 22'. The signal is then directed by circulator 22' into the port 7" of the lower Luneberg lens 36. A Luneberg lens, e.g. lens 36, has the property that when energy is received by one port 7", the energy is dispersed by the action of the lens so as to feed the energy into the ports on the opposite side of the lens 36, e.g. the ports 17" and 18".

The energy is formed by the action of the lens 36 into a wave which exits the lens 36 at ports 17" through 18". This energy is then routed through equal length electrical connections to circulators 24' and 25', which in turn, direct the energy through equal length electrical connections to circulators 24 and 25, respectively. These circulators then direct the energy to radiating elements 17 and 18, respectively. The energy then leaves the antenna as a plane wave indicated in the figure as the transmitted plane phase front. It is apparent, from the circular symmetry of the antenna, that this ability to transmit will be effective for all angles in azimuth and that by the action of the conventional high scanning rate feed systme 37 the transmitted energy can be rapidly scanned in all directions of azimuth.

Simultaneously with the transmission of energy from the antenna system energy can also be received from any direction in azimuth. In the operation of the receiving mode of the reciprocal rapid scan antenna system of this invention an electromagnetic wave is received, for example, by the receiving and radiating elements 17, and 18, and the energy from this incident wave is routed from each focusing element 17 and 18 through equal length electrical connections to circulators 24 and 25, respectively. The energy is then directed by circulators 24 and 25, through another set of equal length electrical connections to the upper Luneberg lens 35. A Lunberg lens, e.g. lens 35, also has the property that when energy from a plane wave is incident and is received, for example, by the ports, 17' and 18', the energy is focused down to a port 7' on the opposite side of the lens 35. The energy then exists from lens through port 7' and is routed by circulator 22 and by circulator 22 to the high scanning rate feed system 37 and into element 22" Where the energy is received by the conventional system 37, which has the capability of receiving as well as transmitting energy. Again, it is obvious from the circular symmetry of the antenna that it is capable of receiving energy for all angles of arrival, and it is also apparent that because there is no need for switching the circulators between the transmit and receive states that it is possible to simultaneously transmit energy and receive energy by the use of this antenna system.

It can, therefore, be seen that the invention very effectively provides a reciprocal, omni-directional, rapid scan antenna system which can simultaneously transmit a signal in any direction in azimuth while at the same time receiving a signal from any independent direction in azimuth. This antenna system can be used in a wide variety of applications such as in radar, IFF, or as a repeater in a microwave system, to name just a few examples.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and the scope of the invcntion as set forth in the appended claims.

What is claimed and desired to be secured by Letters Patent of the United States is:

1. In a reciprocal, omnidirectional, rapid scan antenna system, the combination comprising:

receiving and radiating elements.

high scanning rate feed and receiving means,

first and second signal delay means each having a plurality of ports connected thereto and being equal in number to the number of said elements,

a plurality of nonreciprocal switches being equal in number to the number of said elements,

each of said receiving and radiating elements being connected to a respective port on each delay means and to said high scanning rate feed and receiving means by a separate nonreciprocal switch to transmit signals in any direction in azimuth from said elements simultaneously with the reception of signals from any independent direction in azimuth.

2. The combination of claim 1 wherein said receiving and radiating elements comprise wave-guide horns.

3. The combination of claim 1 wherein said nonreciprocal switches are four-port circulators.

4, The combination of claim 3 wherein each of said circulators is connected to said high scanning rate feed and receiving means by equallength electrical connections.

5. The combination of claim 3 wherein each of said receiving and radiating elements is connected to its respective circulator by equal-length electrical connections.

6. The combination of claim 3 wherein each of said circulators is connected to said first and second delay means by equal-length electrical connections.

7. The combination of claim 1 wherein said receiving and radiating elements are oriented in a complete circular ring.

8. The combination of claim 7 wherein said first and second delay means each comprise a circular Luneberg lens.

9. The combination of claim 8 wherein the diameter of each of said Luneberg lenses is equal to the diameter of said circular ring.

References Cited UNITED STATES PATENTS ELI LIEBERMAN, Primary Examiner.

US. Cl. X.R. 343777, 854 

